SPECIAL PAKTS OF DIAPHRAGM. 487 



the quadratus lumborum and psoas muscles, which give origin to fleshy 

 fibres. 



The arch over the psoas (lig. arcuat. internum/) is the strongest, and 

 is connected by the one end to the tendinous part of the pillar of the dia- 

 phragm, and by the other to the transverse process of the first or the second 

 lumbar vertebra. 



The arch over the quadratus lumborum (lig. arcuat. externum g) is only 

 a thickened part of the fascia covering that muscle, and extends from the 

 same transverse process (first or second lumbar) to the last rib. 



Apertures. There are three large openings for the aorta, the vena cava, 

 and the oesophagus ; with some smaller fissures for nerves and vessels. 



The opening for the aorta (/) is rather behind, than in the diaphragm, 

 for it is situate between the pillars of the muscle and the spinal column : it 

 transmits the aorta, the thoracic duct, and the vena azygos. 



The opening for the oesophagus and the pneumo-gastric nerves (?) is 

 rather above and to the left of the aortic aperture ; it is placed in the 

 muscular part of the diaphragm, and is bounded by the fibres of the pillars 

 as above explained. 



The opening for the vena cava (/?) (Foramen quadratum) is situate in 

 the right division of the central tendon ; and its margins are attached to 

 the vein by tendinous fibres, except at the inner part. 



There is a fissure (/) in each pillar for the three splanchnic nerves ; 

 and through that in the left crus passes also the small azygos vein. 



Dissection. After the diaphragm has been learnt, the ribs that support 

 it on each side may be cut through, and the pieces of the ribs with the 

 fore part of the diaphragm may be taken away, to make easier the dissec- 

 tion of the deeper vessels and muscles. But the posterior part of the dia- 

 phragm with its pillars and arches should be left ; and the vessels ramify- 

 ing on it should be followed back to their origin. 



The large vessels of the abdomen, viz., the aorta and the vena cava, are 

 to be cleaned by removing the fat, the remains of the sympathetic, and 

 the lymphatic glands ; and their branches are to be followed to the dia- 

 phragm, to the kidney and suprarenal body, and to the testicle. In like 

 manner the large iliac branches of the aorta and cava are to be laid bare 

 as far as Poupart's ligament. The ureter and the spermatic vessels are to 

 be cleaned as they cross the iliac artery to the limb ; and on the iliac 

 trunk near the thigh, branches of a small nerve (genito-crural) are to be 

 sought. 



The muscles are to be laid bare on the right side, but on the left side 

 the fascia covering them is to be shown ; and the tat is to be cleared away 

 from about the kidney. 



The psoas muscle, the most internal of all, lies on the side of the spine, 

 with the small psoas superficial to it occasionally. On its surface, and in 

 the fat external to it, the following branches of the lumbar plexus will be 

 found : The genito-crural nerve lies on the front. Four other nerves issue 

 at the outer border the ilio-hypogastric and ilio-inguinal near the top, the 

 external cutaneous about the centre, and the large anterior crural at the 

 lower part. Along the inner border of the psoas the gangliated cord of 

 the sympathetic is to be sought, along with a chain of lumbar lymphatic 

 glands ; and somewhat below the pelvic part of the muscle the obturator 

 nerve may be recognized. External to the psoas is the quadratus lum- 

 borum, and crossing it near the last rib is the last dorsal nerve, with an 



